The Parque Estadual do Prosa (PEP), in Campo Grande, MS, is an urban fragment of savanna (cerrado) and tall savanna woodland (cerradão), with an area of 1,335 km(2), where the population density of brown-nosed coatis is 33.71 individuals/km(2). Our results suggest that seasonality at the PEP causes changes in the availability of resources for coatis, altering their home range areas, their dispersion patterns and their daily behaviour. And our observations regarding male-band associations, agonistic interactions between bands and their daily behaviour emphasize the plasticity of coati social structure, and its potential for future comparative studies.